Abstract
A strong downslope wind event under fine weather condition on 13–15 February 2018 was examined by various observational and high resolution reanalysis datasets during the 2018 Winter Olympic and Paralympic games in Pyeongchang, Korea. High spatio-temporal resolution of wind information was obtained by Doppler lidars, automatic weather stations (AWS), wind profiler, and sounding observations under the International Collaborative Experiments for Pyeongchang 2018 Olympic and Paralympic winter games (ICE-POP 2018). This study aimed to understand the possible generation mechanisms of localized strong wind event across high mountainous areas and in the lee side of mountains associated with the underlying large-scale pattern of a low-pressure system (LPS). The spatial distribution of linear trends for surface wind shows different patterns, exhibiting increased trend in the lee side and a persistent one in mountainous areas with the approaching LPS. Surface wind speed was intensified dramatically from ~3 to ~12 m s−1 (gust was stronger than 20 m s−1 above ground) at a surface station in the lee side (named as GWW). However, the mountainous station at DGW site appeared to have a persistently strong wind (~10 m s−1) during the research period. Budget analysis of horizontal momentum equation and local reanalysis data suggests that the pressure gradient force (PGF) derived by adiabatic warming along the downslope and subsequent hydraulic jump in the lee side of mountains was a main factor in the acceleration of the surface wind at the GWW site. Detailed analysis of the retrieved 3D winds reveals that the PGF also dominate at the DGW site, which causes the persistent strong wind that is related to the channeling effect across the valley areas in the mountain range. The observational evidence presented here shows that the different mechanisms in local areas under the same synoptic condition with LPS are important references in determining the strength and persistence of the orographic-induced strong winds under fine weather condition.
Highlights
In mountain regions, wind is an important atmospheric phenomena as enhanced precipitation may be usually caused by the wind impinging topography (Medina et al, 2007; Yu and Cheng, 2008; Panziera and Germann, 2010; Houze, 2012; Yu and Tsai, 2017; Tsai et al, 2018).topography could significantly affect the behavior of winds to accelerate the wind speed or to change the wind direction
Topography could significantly affect the behavior of winds to accelerate the wind speed or to change the wind direction
The radial winds were sufficiently observed by adjustable scanning strategy in three modes: Plan Position Indicator (PPI), Range Height Indicator (RHI), and Zenith pointing (ZP)
Summary
Wind is an important atmospheric phenomena as enhanced precipitation may be usually caused by the wind impinging topography (Medina et al, 2007; Yu and Cheng, 2008; Panziera and Germann, 2010; Houze, 2012; Yu and Tsai, 2017; Tsai et al, 2018). A few previous studies provided insightful explanations in numerical aspect about the development of the strong wind associated with the downslope windstorm along the northeastern coast of South Korea (in the lee side of the Taebaek Mountain Ranges; TMR). The objective of this study is to use high spatiotemporal resolution of 3D winds and observational data to investigate the fine-scale structural evolution of strong downslope winds over the complex terrain in northeastern part of South Korea (i.e., in the Pyeongchang area ). Doppler lidars were established in this area, which provided more sufficient wind information under fine weather condition
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